Workers lack a "spermatheca", hence can't be inseminated.  They don't call them "sterile" workers for nothing.<Grin>  Kidding aside the Cape bee gets around this by having eggs that "fertilize" themselves.  I believe it was Mackensen, who reported this trait at very low levels in "American" bees of "European" decent, something the Europeans claim they never find.  Not sure of the "reporter" but I'm pretty sure the date was 1948.  My memory, such as it is, works in wierd ways.
BTW, as an after thought, Herr Doktor Ruttner, the one with the "F", I believe, was the one who worked out how they "pull it off", in this case I can recall the "reporter" but not the date.

I'll go crawl back under my rock, PLB can take it from here.  

Rip 

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